// 首页 BLoC — 加载最近日记和心情概览

import 'package:flutter/foundation.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:nuanji_app/data/models/journal_entry.dart';
import 'package:nuanji_app/data/repositories/journal_repository.dart';

// ===== Events =====

sealed class HomeEvent {
  const HomeEvent();
}

/// 加载首页数据（最近日记 + 心情概览）
final class HomeLoadData extends HomeEvent {
  const HomeLoadData();
}

/// 刷新首页
final class HomeRefresh extends HomeEvent {
  const HomeRefresh();
}

// ===== State =====

/// 首页状态
sealed class HomeState {
  const HomeState();
}

final class HomeInitial extends HomeState {
  const HomeInitial();
}

final class HomeLoading extends HomeState {
  const HomeLoading();
}

final class HomeLoaded extends HomeState {
  /// 最近日记（取最新 10 条）
  final List<JournalEntry> recentJournals;

  /// 今日是否已写日记
  final bool hasTodayEntry;

  /// 最近常用心情
  final Mood? topMood;

  /// 连续写日记天数（从日记列表推算）
  final int streakDays;

  /// 本月日记数（spec §3.4 quick-stats）
  final int monthCount;

  /// 总日记数（spec §3.4 quick-stats）
  final int totalCount;

  /// 今日天气（从今日日记中提取，null 则默认晴）
  final Weather? todayWeather;

  const HomeLoaded({
    this.recentJournals = const [],
    this.hasTodayEntry = false,
    this.topMood,
    this.streakDays = 0,
    this.monthCount = 0,
    this.totalCount = 0,
    this.todayWeather,
  });
}

final class HomeError extends HomeState {
  final String message;
  const HomeError(this.message);
}

// ===== BLoC =====

class HomeBloc extends Bloc<HomeEvent, HomeState> {
  final JournalRepository _journalRepo;

  HomeBloc({required JournalRepository journalRepository})
      : _journalRepo = journalRepository,
        super(const HomeInitial()) {
    on<HomeLoadData>(_onLoadData);
    on<HomeRefresh>(_onRefresh);
  }

  Future<void> _onLoadData(
    HomeLoadData event,
    Emitter<HomeState> emit,
  ) async {
    emit(const HomeLoading());
    try {
      final journals = await _journalRepo.getJournals(
        page: 1,
        pageSize: 10,
      );

      // 检查今日是否已写日记
      final today = DateTime.now();
      final hasTodayEntry = journals.any((j) =>
          j.date.year == today.year &&
          j.date.month == today.month &&
          j.date.day == today.day);

      // 推算最常用心情
      final moodCounts = <Mood, int>{};
      for (final j in journals) {
        moodCounts[j.mood] = (moodCounts[j.mood] ?? 0) + 1;
      }
      final topMood = moodCounts.entries
          .fold<MapEntry<Mood, int>?>(null, (a, b) => a == null || b.value > a.value ? b : a)
          ?.key;

      // 推算连续天数
      final streakDays = _calculateStreak(journals);

      // 本月日记数（spec §3.4 quick-stats）
      final monthCount = journals.where((j) =>
          j.date.year == today.year && j.date.month == today.month).length;

      // 总日记数 — 使用仓库计数方法（不受分页限制）
      final totalCount = await _journalRepo.getJournalCount();

      // 今日天气 — 从今日日记中提取
      final todayJournal = journals.firstWhere(
        (j) => j.date.year == today.year &&
               j.date.month == today.month &&
               j.date.day == today.day,
        orElse: () => journals.first, // fallback for type safety
      );
      final todayWeather = hasTodayEntry ? todayJournal.weather : null;

      emit(HomeLoaded(
        recentJournals: journals,
        hasTodayEntry: hasTodayEntry,
        topMood: topMood,
        streakDays: streakDays,
        monthCount: monthCount,
        totalCount: totalCount,
        todayWeather: todayWeather,
      ));
    } catch (e) {
      debugPrint('HomeBloc._onLoadData 失败: $e');
      emit(const HomeLoaded()); // 空状态而非错误，离线友好
    }
  }

  Future<void> _onRefresh(
    HomeRefresh event,
    Emitter<HomeState> emit,
  ) async {
    add(const HomeLoadData());
  }

  /// 从日记列表推算连续写日记天数
  int _calculateStreak(List<JournalEntry> journals) {
    if (journals.isEmpty) return 0;

    final dates = journals.map((j) => j.date).toSet();
    var streak = 0;
    var checkDate = DateTime.now();

    while (dates.contains(DateTime(checkDate.year, checkDate.month, checkDate.day))) {
      streak++;
      checkDate = checkDate.subtract(const Duration(days: 1));
    }

    return streak;
  }
}